The impact of feeding condensed distillers byproducts on rumen microbiology and metabolism*

In vitro fermentation experiments and a feeding trial were conducted to determine how distillers byproducts impact rumen microbiology and metabolism. The in vitro rate of lactic acid disappearance was not stimulated by direct addition of distillers byproducts to mixed rumen contents collected from a steer adapted to a high concentrate diet. However, if animals were fed condensed distillers byproducts for several weeks, rumen microbiology and metabolism were affected. Culturable counts of starch-degrading and lactic acid utilizing bacteria increased, and this coincided with a two-fold increase in the in vitro rate of lactic acid fermentation. These data suggest distillers byproducts could be used to selectively manipulate the rumen microbial population and improve the capacity of the rumen microorganisms to utilize lactic acid, the causative agent of acute ruminal acidosis and morbidity in cattle.